Feeds

Petaflops beater: Nvidia chief talks exascale

Programming for parallel processes

Top 5 reasons to deploy VMware with Tegile

"Power is now the limiter of every computing platform, from cellphones to PCs and even data centres," said NVIDIA chief executive Jen-Hsun Huang, speaking at the company's GPU Technology Conference in Beijing last week. There was much talk there about the path to exascale, a form of supercomputing that can execute 1018 flop/s (Floating Point Operations per Second).

Currently, the world's fastest supercomputer, Japan's K computer, achieves 10 petaflops (one petaflop = a thousand trillion floating point operations per second), just 1 per cent of exascale. The K computer consumes 12.66MW (megawatts), and Huang suggests that a realistic limit for a supercomputer is 20MW, which is why achieving exascale is a matter of power efficiency as well as size. At the other end of the scale, power efficiency determines whether your smartphone or tablet will last the day without a recharge, making this a key issue for everyone.

Huang's thesis is that the CPU, which is optimised for single-threaded execution, will not deliver the required efficiency. "With four cores, in order to execute an operation, a floating point add or a floating point multiply, 50 times more energy is dedicated to the scheduling of that operation than the operation itself," he says.

Jen-Hsun Huang, photo Tim Anderson

Power limits: NVIDIA chief executive Jen-Hsun Huang

"We believe the right approach is to use much more energy-efficient processors. Using much simpler processors and many of them, we can optimise for throughput. The unfortunate part is that this processor would no longer be good for single-threaded applications. By adding the two processors, the sequential code can run on the CPU, the parallel code can run on the GPU, and as a result you can get the benefit of the both. We call it heterogeneous computing."

He would say that. NVIDIA makes GPUs after all. But the message is being heard in the supercomputing world, where 39 of the top 500 use GPUs, up from 17 a year ago, and including the number 2 supercomputer: Tianhe-1A in China. Thirty-five of those 39 GPUs are from NVIDIA.

At a mere 2.57 petaflops though, Tianhe-1A is well behind the K computer, which does not use GPUs. Does that undermine Huang's thesis? "If you were to design the K computer with heterogeneous architecture, it would be even more," he insists. "At the time the K computer was conceived, almost 10 years ago, heterogeneous was not very popular."

Using GPUs for purposes other than driving a display is only practical because of changes made to the architecture to support general-purpose programming. NVIDIA's system is called CUDA and is programmed using CUDA C/C++. The latest CUDA compiler is based on LLVM, which makes it easier to add support for other languages. In addition, the company has just announced that it will release the compiler source code to researchers and tool vendors. "It's open source enough that anybody who would like to develop their target compiler can do it," says Huang.

Another strand to programming the GPU is OpenACC, a set of directives you can add to C code that tell the compiler to transform it to parallelised code that runs on the GPU when available. "We've made it almost trivial for people with legacy applications that have large parallel loops to use directives to get a huge speedup," claims Huang.

OpenACC is not yet implemented, though it is based on an existing product from the Portland Group called PGI Accelerator. Cray and CAPS also plan to have OpenACC support in their compilers. These will require NVIDIA GPUs to get the full benefit, though it is a standard that others could implement. There is a programming standard called OpenCL that is already supported by multiple GPU vendors, but it is lower level and therefore less productive than CUDA or OpenACC.

Top 5 reasons to deploy VMware with Tegile

Next page: Blurred lines

More from The Register

next story
Azure TITSUP caused by INFINITE LOOP
Fat fingered geo-block kept Aussies in the dark
You think the CLOUD's insecure? It's BETTER than UK.GOV's DATA CENTRES
We don't even know where some of them ARE – Maude
729 teraflops, 71,000-core Super cost just US$5,500 to build
Cloud doubters, this isn't going to be your best day
Want to STUFF Facebook with blatant ADVERTISING? Fine! But you must PAY
Pony up or push off, Zuck tells social marketeers
Oi, Europe! Tell US feds to GTFO of our servers, say Microsoft and pals
By writing a really angry letter about how it's harming our cloud business, ta
SAVE ME, NASA system builder, from my DEAD WORKSTATION
Anal-retentive hardware nerd in paws-on workstation crisis
Astro-boffins start opening universe simulation data
Got a supercomputer? Want to simulate a universe? Here you go
prev story

Whitepapers

Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Protecting against web application threats using SSL
SSL encryption can protect server‐to‐server communications, client devices, cloud resources, and other endpoints in order to help prevent the risk of data loss and losing customer trust.
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.